Which Hex editor do you guys prefer to use? They're all doing my head in at the moment.

That last sentence makes me think that you're looking for an easy to use hex editor, ja? If so, you won't exactly find one that'll walk you through anything, the ease of use is more on the side of how much you know about hexadecimal than the user interface of the hex editor itself.

I personally use XVI32, only because I heard about it one day and downloaded it, not because it's the best or anything like that. It works, and it works well, and that's pretty much all I can ask for in a free hex editor.